Method and apparatus for winding spiral springs

ABSTRACT

METHOD AND APPARATUS FOR WINDING A SPIRAL SPRING ASSEMBLY FROM A PLURALITY OF LENGTHS OF SPRING METAL BANDS, CHARACTERIZED THAT THE BAND LENGTHS ARE SUPPLIED THROUGH AN OPENING CONTAINED IN A BASE PLATE, EACH OF THE BANDS BEING TWISTED OR BENT ABOUT AN INCLINED AXIS TOWARD AN EDGEWISE-SUPPORTED POSITION NORMAL TO THE WINDING FACE OF THE BASE PLATE. THE LEADING PORTION OF THE BAND IS THEN GUIDED THROUGH AN AXIAL SLIT IN A WINDING DRUM ARRANGED CONCENTRICALLY ABOUT THE SUPPLY OPENING, SO THAT UPON ROTATION OF THE DRUM RELATIVE TO THE BASE PLATE, THE BANDS ARE WOUND UPON THEMSELVES TO FORM A CONVOLUTE SPRING ASSEMBLY. THE BANDS ARE SYMMETRICALLY DISCHARGED FROM THE SUPPLY OPENING EITHER AXIALLY OR IN A UNIFORMLY SKEWED MANNER. IN THE LATTER CASE, DEPENDING ON THE CHARACTERISTICS OF THE METAL FROM WHICH THE SPRING BANDS ARE FORMED, THE DRUM IS ROTATED EITHER IN THE DIRECTION OF SKEW OR IN A DIRECTION OPPOSITE TO THE DIRECTION OF SKEW. MEANS ARE PROVIDED FOR LOCKING THE TRAILING PORTIONS OF THE BANDS IN THE SUPPLY OPENING DURING THE WINDING OPERATION.

Sept.'28,- 1971 GREmER EI'AL 3,608,349

METHOD AND APPARATUS FOR WINDING SPIRAL SPRINGS Filed Dec. 18, 1969 .5Sheets-Shoot 1 INVENTORS RUDOLF GREINER WALTER SCHWEIZER LOTHAR'KIESEWETTER gm gm 14m may Sept. 28, 1971 E N ETAL 3,608,349

' METHOD AND APPARATUS FOR WINDING SPIRAL SPRINGS Filed Dec. 18, 1969 5Sheets-Shoot 2 Fig. 2

INVENTORS RUDOLF GREINER WALTER SCHWEIZER LOTHAR KIESEWETTER Sept. 28,1971 R. GREINER EI'AL 3,608,349

I METHOD AND APPARATUS FOR WINDING SPIRAL SPRINGS Filed Dec. 18, 1969 5SheetsSh0et 3 INVENTORS RUDOLF GREINER WALTER SCHWEIZER LOTHARKIESEWETTER BY Km 5% Alrnmmerv Sept. 28, 1971 GRE|NER ETAL 3,608,349

METHOD AND APPARATUS FOR WINDING SPIRAL SPRINGS Filed Dec. 18, 1969 v 5Sheets-Sheet INVENTORS RUDOLF GREINER WALTER SCHWEIZER LOTHARKIESEWETTER 1m M U P 23, 1971 R. GREINER EI'AL 3,608,349

METHOD AND APPARATUS FOR WINDING SPIRAL SPRINGS I Filed Dec. 18, 1969 5Sheets-Shoot 5 INVENTORS RUDOLF GREINER WALTER SCHWEIZER LOTHARKIESEWETTER A TTORNEY 3,608,349 METHOD AND APPARATUS FOR WINDING SPIRALSPRINGS Rudolf Greiner, Allmengasse 41A, CPI-4900, Langenthal,

Switzerland, and Walter Schweizer and Lothar K esewetter, Berlin,Germany; said Schweizer and Kresewetter assignors to said Greiner FiledDec. 18, 1969, Ser. No. 886,203 Claims priority, applicationSwitzerland, Jan. 27, 1969, 1,171/69 Int. Cl. B21d 11/06, 11/10; B21f3/08 US. Cl. 72-146 16 Claims ABSTRACT OF THE DISCLOSURE Method andapparatus for winding a spiral spring assembly from a plurality oflengths of spring metal bands, characterized that the band lengths aresupplied through an opening contained in a base plate, each of the bandsbeing twisted or bent about an inclined axis toward anedgewise-supported position normal to the winding face of the baseplate. The leading portion of the band is then guided through an axialslit in a winding drum arranged concentrically about the supply opening,so that upon rotation of the drum relative to the base plate, the bandsare wound upon themselves to form a convolute spring assembly. The bandsare symmetrically discharged from the supply opening either axially orin a uniformly skewed manner. In the latter case, depending on thecharacteristics of the metal from which the spring bands are formed, thedrum is rotated either in the direction of skew or in a directionopposite to the direction of skew. Means are provided for locking thetrailing portions of the bands in the supply opening during the windingoperation.

It is known in the prior art to manufacture small coil springssuch asthose required for all types of measuring instruments and also forclocksby shaping in a joint winding operation a plurality of individualspring bands which have previously been severed to a predeterminedlength, which bands are then wound within each other to define the coilsprings. In this known apparatus, use is made of a rotatably positionedwinding mandrel which is provided at its free end with a plurality ofuniformly circumferentially distributed fastening slits. For each set ofspring bands to be wound within each other there is provided also anenclosed winding drum which comprises a central guide aperture at thebottom of the enclosure and which is provided at the edge of theenclosure with a plurality of guide slits uniformly distributed in thecircumferential direction, the number of the guide slits being equal tothe number of fastening slits disposed in the winding mandrel.

In the known apparatus, before each winding operation is carried out, aninitially empty winding drum is inserted, by means of the guide aperturethereof, over the winding mandrel in a manner such that the end face ofthe latter projects upwardly into the inner space of the spring housing.One end of a spring band is then introduced by hand into each fasteningslit of the winding mandrel. Furthermore, the corresponding spring bandmust be placed within the corresponding guide slit of the springhousing, respectively. When the winding mandrel and the winding drum areequipped with the required number of spring bands in a concentricsymmetrical fashion, the winding mandrel is rotated while the windingdrum is maintained stationary until the inner space of the drum is fullycoiled. The drum, together with the spring bands spirally coiledtherein, is then drawn off the winding mandrel in an upward directionfor subsequent thermal treatment as is customary in the art. The windingmandrel is then ready to receive United States Patent O a furtherwinding drum which is likewise initially empty, so that the next set ofcoil springs can be made in the manner described above.

The universally used method of winding coil springs which has beenbriefly described above is rather inefficient and costly by reason ofthe fact that essential operations thereof are time-consuming andnormally must be performed by hand. Moreover, with the aid of this knownmethod it is not possible to make coil springs which have a very smallinside diameter inasmuch as the winding mandrel itself must have acertain minimal diameter in order to be actually adapted to absorb thetorsional moment required for the coiling operation. On the other hand,coil springs having a relatively small inside diameter are verydesirable for numerous fields of application.

Accordingly, the primary object of the present invention is to providean improved method and apparatus for winding coil springs wherein aplurality of spring bands extend, during the Winding operation, throughthe inner space of a winding drum in a concentric symmetrical fashionand are each individually guided by means of corresponding guide slotsperipherally disposed within the drum. The disadvantages and drawbacksof the prior art winding methods as outlined above can be effectivelyobviated, in accordance with the present invention, by virtue of theimproved arrangement wherein the spring winding drum is arrangedconcentrically about a supply opening through which given lengths of thespring bands are supplied. The spring bands are secured against rotationwithin the supply opening and are introduced into the inner space of thespring winding drum in a direction either normal to or skewed relativeto the opening in the winding face of the base plate. The spiral bandwinding operation is effected by rotary movement of the winding drumrelative to the base plate, the inner end portions of each of the springbands being initially bent upon discharge from the supply opening aboutan axis inclined with respect to the longitudinal extension of thesespring bands.

In accordance with the preferred embodiment of the method and apparatusof the present invention, it is further proposed that the inner endportions of the coil springs be severed only after the cempletion of thecoiling or winding operation from the spring bands extending through theinlet opening and that, after the removal of the spring housing filledwith a set of coil springs, the remaining spring bands which stillextend through the inlet opening be further supplied in the lengthsnecessary for making a new set of coil springs.

Other objects and advantages of the present invention will becomeapparent from a study of the following specification, When viewed in thelight of the accompanying drawing, in which:

FIG. 1 is a perspective view of the base plate and the winding drum of afirst embodiment of the invention, wherein the spring bands areinitially discharged axially from the supply opening disposed in thebase plate in a direction extending normal to the intended windingplane;

FIG. 2 is a detailed schematic top plan view of the supply opening inthe base plate according to FIG. 1, wherein the equally illustratedinner end portions of the spring bands represent different stages at thebeginning of the winding operation;

FIG. 3 is a top plan view analogous to that of FIG. 2, of a secondembodiment of the invention, wherein the spring bands initially emergefrom the supply opening in a skewed orientation generally parallel withthe intended winding plane;

FIG. 4 is a perspective view of the inner end portion of one of thespring bands according to FIG. 3, showing the arising deflection aboutan inclined axis relative to the winding face of the base plate;

FIG. 5 is a top plan view of the inner end portions and the adjacentinner turns of the spirally and telescopically wound spring bands woundin the direction of skew as indicated by the arrow in FIG. 3;

FIG. 6 is a top plan view of the inlet opening disposed in the baseplate from which the spring bands emerge in a skewed fashion as in FIG.3, but wound in a direction opposite to the direction of skew;

FIG. 7 is a perspective view of the inner end portions of a pair of thespring bands according to FIG. 6, indicating the initial bendingdeflections of the bands about axes inclined to the winding face;

FIG. 8 is a top plan view of the inner end portions and the adjacentinner turns of the spirally wound spring bands formed by the windingoperation of FIGS. 6 and 7; and

FIG. 9 is a perspective view of the base plate and the winding drum in afurther embodiment wherein the spring bands emerge from the supplyopening in a direction extending normal to the winding plane, as in FIG.1, said inlet opening comprising a plurality of radially outwardlyextending slits for securing the spring bands against rotation, withoutthe aid of an additional clamping member.

The construction of the apparatus or device according to FIG. 1 includesa base plate 1 which is secured to a stationary frame or stand. Thisbase plate 1 contains a circular supply opening 2 through which aplurality of spring bands 6 are supplied in a concentric symmetricalmanner. Generally it is customary to use six such spring bands 6, as isapparent from the top plan view of FIG. 2. In FIG. 1, on the other hand,only three of the aforementioned spring bands 6 have been shown for thesake of greater clarity of illustration. When six spring bands 6 areused, the radius of the inlet opening is chosen to be approximatelyequal to the width of the blades of the spring bands 6. When it isdesired to make coil springs having the usual dimensions, the springbands 6 needed therefor have, for example, a blade width of 0.2millimeter and a blade thickness of approximately 0.03 millimeter.

Also mounted in the afore-mentioned frame beneath the base plate 31 arethe band supply means (not shown) by means of which all of the springbands 6 are supplied simultaneously through the inlet opening 2 upwardlyin a direction extending normal to the upper winding face of the baseplate 1. In the present embodiment, the spring bands 6 conveyed to thefeeding device are reeled oif six storage drums which are rotatablyconnected with the frame. The supply drums are preferably arrangedsymmetrically in a concentric manner with respect to the axis of thesupply opening 2.

Prior to the beginning of each Winding operation, the spring bands 6 aresupplied upwardly from the supply opening 2 for a distance at least asgreat as the length of the spiral springs to be wound. Furthermore, itis advisable and expedient to assure already during this feedingoperation that each of the spring bands 6, as viewed from the inletopening 2, falls outwardly in a radial direction, such as has beenindicated in connection with the two spring band pieces or portions 6directed toward the left in FIG. 1. For the sake of a clearerillustration, the drawing does not shown respectively the full requiredlengths of the spring band portions but only the inner parts thereof.When the necessary feed of the spring bands 6 has taken place, they arepressed against the periphery of the supply openings 2, by means of aclamping member 10, as shown in FIGS. 1 and 2, and thereby are securedagainst rotation at the base plate 1. A pin member 10 which is providedwith a conical head and is displaceable in the axial direction of thesupply opening 2 serves as the clamping member. The means for axiallyactuating this clamping member 10 are conventional and have not beenshown in detail in the drawing.

In the embodiment illustrated in FIG. 1, the base plate \1 furthercontains an annular groove 7 concentrically arranged relative to thesupply opening 2 and adapted to .4 receive the free tubular edge portionof the rotary winding drum 3. While the winding drum 3 may have thecustomary enclosed configuration, it is preferably of the openendedconstruction illustrated in FIG. 1, said drum containing guide slits =5peripherally arranged in the lower tubular portion of the winding drum.The winding drum is normally arranged with the edge 4 thereof extendingwithin the annular groove 7 so that each of the radially out wardlydirected spring bands 6 extends through a corresponding guide slit 5without being actually clamped at that time.

For the purpose of carrying out the winding operation,

the winding drum 3 is rotated, whereby the spring bands 6 projecting outof the guide slits 5 are carried along in the winding direction 8. Atthat time each of the spring bands 6 undergoes within the drum 3 atwisting effect about an axis A--A being inclined with respect to thelongitudinal extension thereof, as has been illustrated in FIG. 1 forthe spring band 6 pointing toward the right. Owing to the progressiverotation of the spring housing 3, this initial twist changes into anever more marked deflection which is produced directly at the inner endportion of the spring band emerging from or leaving the inlet opening 2.The different stages of this bending or twisting operation and procedurehave been shown in FIG. 2, starting from the spring band at the upperright and rectilinearly falling outwardly, and viewing thereafter thespring bands 6 following the winding direction 8. Hence, the springbands 6 are transferred, in the area or region outside of the inner endportions thereof, into an edgesupported upright position normal to theupper side of the base plate 1, in which the winding operation isterminated. This winding operation is completed when the inner space ofthe winding drum 3 is filled up to the box edge 4 with interwound coilsprings. Normally, also the leading end portions of the spring bands 6which initially extended through the guide slits 5 are drawn into theinner space of the spring housing 3 immediately prior to the terminationof the winding operation. Only thereafter will the inner end portions ofthe coil springs be separated from the spring bands 6 projecting throughthe inlet opening 2. This may be accomplished, for example, byintroducing through the guide aperture 9 of the spring housing 3 acorresponding cutting, punching, or boring tool which carries out thisseparating or severing procedure. The aforementioned separation may alsobe obtained, however, without the aid of a separate tool simply byfurther rotating, after the completion of the Winding operation, thealready completely filled winding drum 3 in the winding direction. Theinner end portions of the coil springs will then automatically be tornoff at the point of the deflections being deformed to bends proper. Inmost cases after the winding operation has been completed the severedend portions of the spring bands 6 emerge from the guide slits 5.Following separation of the coil springs from the trail- 1ng endportions of the spring bands 6 projecting out of the inlet opening 2,the winding drum 3 together with the coil springs wound therein arelifted oif the base plate 1 and subjected to the customary thermaltreatment. Thereafter, subsequent given lengths of the spring bands 6are supplied through the inlet opening 2 for a further winding operationin the manner described above. It is obv ous that these operating stepsare susceptible to automatron to a great extent.

The method described hereinbefore may be modified, however, in variousways and thus afiFord further advantages. It may thus be desirable tohave the spring bands 6 emerge from the inlet opening 2 in a skewedmanner relative to the winding plane defined by the upper yvinding faceof the base plate 1, such as has been shown 1n the top plan view of FIG.3. Such a skewed emergence of the spring bands 6 assures on the one handthat the bands 6 will be arranged automatically in a concentricsymmetrical manner without the aid of or recourse to specific measuresand will initially be generally parallel with the base plate windingface. If desired, the supply opening may have a corresponding conicalcross-sectional configuration. There will arise, however, differentconditions for the winding operation depending upon the windingdirection of the winding drum 3 relative to the base plate 1.

When the winding direction 8 according to FIG. 3 corresponds with thedirection of skew of the spring bands 6 as initially discharged into thewinding plane, each of the bands will be bent off at the inner endportion thereof about the axis AA inclined with respect to thelongitudinal extension thereof, as shown by way of example in FIG. 4.When the winding operation is completed, the coil assembly of FIG. 5will result for the inner end portions of the spring bands 6 and for theadjacent inner coil spring winding turns, as viewed in the top planview. Accordingly, the inner deflections of the spring bands 6 areproduced to avoid a marked bend, which is particularly desirable whenthe spring bands 6 are made from nonferrous metals or alloys.

For those spring bands 6, however, which are made from ferrous metals orthe alloys thereof, the winding direction 8 is opposite to that shown inFIGS. 3 to 5 (i.e., in a direction opposite to the direction of skew ofthe bands relative to the winding face). At the beginning of the windingoperation, the spring bands 6 are twisted according to FIG. 6. As thewinding operation proceeds, each of the spring bands 6 is sharply bentoff about the inclined axis AA in a manner similar to a bend or break,according to FIG. 7. The resulting coil assembly is illustrated in FIG.8.

It is assumed for the apparatus shown in FIGS. 1 through 8 that duringthe winding operation the spring bands 6 are securely held againstrotation within the inlet opening 2 by means of a separately actuatedaxially displaceable clamping member 10. Referring now to FIG. 9, amodified construction is illustrated which does not require a clampingmember 10. This is rendered possible by virtue of the fact that thecentral inlet opening comprises a number of radially outwardly directedslits 2a corresponding to the number and cross-sectional dimensions ofthe spring bands 6 which are to extend therethrough. It is quite obviousthat by virtue of the radial arrangement of the slits, an axialemergence of the spring bands 6 is assured which is secured againstrotation with out the aid of any further expedients. For clarity, onlytwo spring bands 6 have been shown in FIG. 9. The winding operation isthen accomplished by means of the rotary winding drum 3 in essentiallythe same manner as has been referred to in connection with FIG. 1 above.For each of the spring bands 6, there is also a marked bent-off area ordeflection at the trailing inner end portion thereof about an axis AAinclined with respect to the longitudinal extension of the respectivespring band.

An advantageous feature of the invention common to all of the variousembodiments mentioned herein consists in that the inside diameter of thecoil springs may be as small as possible, the only limiting criteriabeing the dimensions of the opening 2.

While in accordance with the provisions of the Patent Statutes, thepreferred form and embodiments of the invention have been illustratedand described, it will be apparent to those skilled in the art thatvarious changes and modifications may be made without deviating from theinventive concept.

We claim:

1. Apparatus for winding a coil spring assembly from a plurality ofmetal bands, comprising a base plate (1) having a winding facecontaining a supply opening through which given lengths of the bands (6)are supplied in a circumferentially spaced symmetrical manner;

a winding drum (3) including a tubular portion arranged concentricallyrelative to the axts of said supply opening, said tubular portioncontaining a plurality of circumferentially spaced axial guide slots(5), each of said bands immediately following discharge from said supplyopening being deformed about an axis (A--A) that is inclined relative tosaidwinding face toward a winding position normal to said winding face,the leading portions of said band lengths being then guided in saidwinding positions radially outwardly through corresponding ones of saidguide slots, respectively;

and means for rotating said winding drum relative to said base plate towind said band lengths to define a convolute spring assembly.

2. Apparatus as defined in claim 1, and further including means forlocking trailing portions of said band lengths within said supplyopening during the spring winding operation.

3. Apparatus as defined in claim 2, and further including means fordischarging said bands from said supply opening initially in the axialdirection relative to said supply opening.

4. Apparatus as defined in claim 2, and further including means fordischarging said bands from said supply opening symmetrically in aninitially skewed direction relative to the axis of said supply openingand with an orientation generally parallel with the winding face of saidbase plate.

5. Apparatus as defined in claim 4, wherein the direction of rotation ofthe winding drum corresponds with the direction in which the bands areinitially skewed relative to the supply opening.

6. Apparatus as defined in claim 4, wherein the direction of rotation ofthe winding drum is opposite to the direction in which the bands areinitially skewed relative to the supply opening.

7. Apparatus as defined in claim 2, wherein said supply opening isgenerally circular, and further wherein said means for locking portionsof said bands in said supply opening comprises a clamping member (10)movable axially of and adapted to extend at least partially within saidsupply opening, whereby said band portions are clamped to the wall ofsaid supply opening.

8. Apparatus as defined in claim 2, wherein said supply openingcomprises a plurality of radially arranged guide slots (2a) throughwhich said bands are supplied, respectively, said bands being locked insaid slots upon deformation of said bands about their respective angularbending axes.

9. Apparatus as defined in claim 1, wherein said drum is open at the endadjacent the winding face of said base plate to permit edgewise supportof the bands by said winding face during the winding operation, saidbase plate containing a circular groove (7) concentric with said supplyopening for receiving the free edge of the tubular portion of saidwinding drum.

10. The method of winding bands of spring metal to define a convolutespring assembly, comprising feeding given lengths of a plurality of saidbands in circumferentially spaced symmetrical arrangement through asupply opening contained in the winding face of a base plate; bendingeach of the bands immediately adjacent the supply opening about an axis(AA) inclined to the winding face of said base plate toward a positionin which the band is normal to said Winding face;

guiding the leading portions of the band lengths through guide slotscontained in and extending axially of a winding drum arrangedconcentrically about said supply opening;

and rotating the drum relative to said base plate to wind the bandlengths to define a convolute stacked assembly.

11. The method as recited in claim 10, wherein the 7 bands are supportedin an edgewise manner by the winding face ofthe base plate during theWinding operation.

12. The method as defined in claim 10, and further including the finalstep of severing the portions of the bands adjacent the supply opening.

13. The method as defined in claim 10, and further including the step oflocking the trailing portions of the band lengths to the base plateprior to rotation of the drum.

14. The method as defined in claim 13, wherein the band lengths areinitially discharged symmetrically from the supply opening in a skewedorientation generally parallel with the winding face of the base plate.

15. The method as defined in claim 14, wherein the References CitedUNITED STATES PATENTS 443,256 12/1890 Logan 29-173 LOWELL A. LARSON,Primary Examiner US. Cl. X.R. 29-173

